Packaged products of mushrooms contained in a modified gas atmosphere and methods and apparatus for making the same

ABSTRACT

Packaged products comprising (a) a sealed container, (b) mushrooms in the container, and a gas atmosphere, wherein the gas includes about 0% to 5% by volume oxygen, about 1% to 20% by volume carbon dioxide, about 0% to 20% by volume hydrogen and at least about 50% by volume nitrogen is provided. Methods of making extended shelf-life packaged mushroom products and apparatus for packaging the mushrooms are further provided.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/645,381 filed Jan. 19, 2005, the disclosure ofwhich is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention generally concerns packaged products comprisingvegetables and fruits in a modified gas atmosphere to preservefreshness, methods for the production of the packaged products andapparatus for making the packaged products.

BACKGROUND OF THE INVENTION

The market for mushrooms has been growing in recent years. Consumersdemand fresh mushrooms not only for their taste, but also for theirhealth benefits. According to one report, 86% and 70% of Americanfamilies regularly purchase button mushrooms and exotic species,respectively.

Many consumers are interested in the nutritional and medicinal aspectsof mushrooms. In particular, mushrooms, especially exotic species, are arich source of proteins, carbohydrates (especially polysaccharides),vitamins (in particular, B and C vitamins), minerals and are low in fat.Stamets (2000). However, the shelf-life of mushrooms, especially exoticspecies, is relatively short. Therefore, there is a need to investigatenew methods to extend the shelf-life of such mushrooms.

The present invention explores the use of modified atmosphereenvironments along with refrigeration to extend the shelf-life andpreserve the microbial quality of exotic mushrooms for a longer periodof time, which may provide a substantial savings for mushroom retailers.

SUMMARY OF THE INVENTION

An aspect of the present invention relates to packaged productscomprising (a) a sealed container, (b) mushrooms in the container, and agas atmosphere, wherein the gas comprises about 0% to 5% by volumeoxygen, about 1% to 20% by volume carbon dioxide, about 0% to 20% byvolume hydrogen and at least about 50% by volume nitrogen.

A further aspect of the invention relates to methods of making extendedshelf-life packaged mushroom products, comprising packaging mushrooms ina sealed container together with a gas atmosphere wherein the gasatmosphere comprises about 0% to 5% by volume oxygen, about 1% to 20% byvolume carbon dioxide, about 0% to 20% by volume hydrogen and at leastabout 50% by volume nitrogen.

An additional aspect of the invention relates to apparatus for packagingmushrooms comprising a plurality of processing stations for (a) removingexisting air from a package comprising mushrooms and (b) adding to thepackage a gas mixture which comprises about 0% to 5% by volume oxygen,about 1% to 20% by volume carbon dioxide, about 0% to 20% by volumehydrogen and at least about 50% by volume nitrogen.

The present invention is described in greater detail in the drawingsherein and the specification set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Graphs presenting data showing aerobic (A) and anaerobic (B)microbial growth in mushroom samples stored under a modified atmospherecontaining no oxygen (MA1), a modified atmosphere containing 3% oxygen(MA2) and/or Air (CO).

FIG. 2. Schematic illustrating a multi-step procedure for assembling apackaged product comprising (a) a sealed container, (b) mushrooms in thecontainer, and a gas atmosphere, wherein the gas comprises about 0% to5% by volume oxygen, about 1% to 20% by volume carbon dioxide, about 0%to 20% by volume hydrogen and at least about 50% by volume nitrogen.

FIG. 3. Schematic illustrating processing stations employed in thestepwise assembly of packaged products comprising (a) a sealedcontainer, (b) mushrooms in the container, and a gas atmosphere, whereinthe gas comprises about 0% to 5% by volume oxygen, about 1% to 20% byvolume carbon dioxide, about 0% to 20% by volume hydrogen and at leastabout 50% by volume nitrogen.

DETAILED DESCRIPTION

The foregoing and other aspects of the present invention will now bedescribed in more detail with respect to other embodiments describedherein. It should be appreciated that the invention can be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

The terminology used in the description of the invention herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of the invention. As used in the description ofthe embodiments of the invention and the appended claims, the singularforms “a,” “an” and “the” are intended to include the plural forms aswell, unless the context clearly indicates otherwise. As used herein,the phrase such as “about X to Y” means “about X to about Y” and alsorefers to a range of values from about X to about Y.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

It will be understood that steps comprising the methods provided hereincan be performed independently or at least two steps can be combinedwhen the desired outcome can be obtained.

Further, embodiments of the present invention may be described hereinwith reference to illustrations that are schematic illustrations ofidealized embodiments of the present invention. As such, variations fromthe illustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, embodiments of the presentinvention should not be construed as limited to the particulardepictions illustrated herein but are to include deviations in shapes,sizes, processes etc. that result, for example, from employing suitablemanufacturing techniques.

All publications, patent applications, patents and other referencescited herein are incorporated by reference in their entireties.

“Gas atmosphere” as used herein refers to an environment including atleast one gaseous element.

“Oxygen-impermeable” as used herein refers to the limited passage ofoxygen through the medium of interest. In some instances, oxygen doesnot pass through the medium of interest. In the U.S., gas permeabilitycan be measured in cc per 100 square inches per 24 hours at 73° F. andone atmosphere of pressure (see American Society for Testing Materialsor “ASTM” D1434-66) and can be further expressed as a function ofthickness measured in mils. In shorthand, the value can be expressed incc's with the other units being understood.

“Shelf-life” as used herein refers to the time frame over which a foodproduct can be relied upon to retain its quality characteristicsincluding, but not limited to, remaining edible, retaining a desirabletexture, free from noticeable discoloration, malodor or harmfuldegradation or contamination by microorganisms.

“Conventional manner of packaging” as used herein refers to packagingproduce in a standard packaging container as understood by those ofordinary skill in the art, for example, overwrapping the container witha polymer material, such as polyethylene or polyvinyl chloride, othersuitable materials and storing the wrapped container usually atrefrigeration temperatures for up to seven days.

“Refrigerated storage” as used herein refers to an environment thatmaintains an ambient temperature that is low enough to detrimentallyaffect growth of spoilage microorganisms. An exemplary temperature rangeis about 2° C. to 8° C.

“Microbial qualities” as used herein refer to the extent of aerobic andanaerobic bacterial growth as well as the growth of other spoilagemicroorganisms such as yeasts and molds.

“Sensory qualities” as used herein refer to qualities pertaining tosensory perception including, but not limited to, odor, color, texture,etc.

In view of the foregoing, embodiments according to the present inventionrelate to packaged products comprising (a) a sealed container, (b)mushrooms in the container, and (c) a gas atmosphere, wherein the gasmay comprise about 0% to 5% by volume oxygen, about 1% to 20% by volumecarbon dioxide, about 0% to 20% by volume hydrogen and at least about50% by volume nitrogen. In particular, the gas may comprise about 0, 1,2, 3, 4 or 5% by volume oxygen; about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, or 20% by volume carbon dioxide; about0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or20% by volume hydrogen; and at least about 50, 60, 70, 80 or 90% byvolume nitrogen. In some embodiments, the gas comprises less than about5% by volume oxygen, about 3% to 12% by volume carbon dioxide, about 0%to 10% by volume hydrogen and at least 70% by volume nitrogen. In otherembodiments, the gas comprises less than about 0.5% by volume oxygen,and can comprise less than about 0.1% by volume oxygen. In furtherembodiments, the gas comprises about 3% by volume oxygen, about 10% byvolume carbon dioxide and about 87% nitrogen. In still otherembodiments, the gas comprises about 10% carbon dioxide, about 10%hydrogen and about 80% nitrogen.

According to the present invention, the gas may be added to the sealedcontainer concurrently with the addition of the mushrooms.Alternatively, the gas may be added to the container after the mushroomshave been added to the container.

Mushrooms suitable for packaging according to the present inventioninclude any variety of edible mushrooms. Exemplary mushrooms include,but are not limited to, Armillaria mellea, Agaricus bisporus (commonbutton mushrooms), Boletus edulis, Cordyceps sinensis, Coriolusversicolor, Flammulina velutipes (Enokitake), Ganoderma lucidum,Hericium erinaceus, Hypsizygus marmoreus (Bunashimeji), Auriculariaauricula-Judae, Phellinus linteus, Pleurotus ostreatus (Hiratake),Grifola frondosa (Bunashimeji), Agaricus campestris, Lentinus edodes(Shiitake), Tremella fuciformis, Volvariella volvacea and Pholiotanameko (Nameko). In some embodiments, the edible mushrooms are commonmushrooms or exotic mushrooms. An exemplary common mushroom includes,but is not limited to, button mushrooms. Exemplary exotic mushroomsinclude, but are not limited to, pom pom, portabella, shiitake andcombinations thereof. The present invention further contemplatespackaging of other vegetables and fruits. Exemplary vegetables include,but are not limited to, green leaf vegetables such as lettuce, spinach,broccoli, kale, collard green, mustard green, celery, cucumber, carrotsand cabbage. Exemplary fruits include, but are not limited to, apples,oranges, grapefruit, lemons, pineapples, strawberries, tomatoes,blueberries, peaches, grapes, raspberries, plums, and cherries.

In some embodiments, packaged products comprising a sealed container,mushrooms in the container, and a gas atmosphere as described above,have a shelf-life of at least 15 days when maintained in a cooledenvironment, such as refrigerated storage. In other embodiments, thepackaged products have a shelf-life of at least 15 days when stored in acooled environment having a temperature of about 4° C. In still otherembodiments, the packaged products have a shelf-life of 21 days whenstored in a cooled or refrigerated environment having a temperature, forexample, at about 4° C. In other embodiments, the shelf-life of thepackaged product can be extended up to about 25 days when stored incooled or refrigerated temperatures, for example, at about 4° C.

In further embodiments, the packaged products comprising a sealedcontainer, mushrooms in the container, and a gas atmosphere as describedabove, exhibit decreased growth of bacteria and other spoilagemicroorganisms compared. to a packaged product packaged in aconventional manner. In particular, addition of a gas atmosphere asdescribed above decreases growth of aerobic bacteria, i.e., bacteriarequiring oxygen for growth and survival, and anaerobic bacteria, i.e.,bacteria that do not require oxygen for growth and survival, and alsodecreases growth of other spoilage microorganisms including any type ofmicroorganism that acts to spoil food, such as yeasts and molds,compared to products packaged according to a conventional manner ofpackaging mushrooms. In some embodiments, the packaged products exhibitimproved microbial qualities compared to a packaged product packaged ina conventional manner. More specifically, at least a one log reductionis achieved in the amount of aerobic bacteria contained in the packagedproduct when stored at about 4° C. for at least 3 days compared to apackaged product packaged in a conventional manner when stored at about4° C. for at least 3 days.

Methods of packaging fruits and vegetables, in particular mushroomsaccording to embodiments of the present invention, entail using standardpackaging materials which may vary in size and include a wide variety ofpackaging shapes and materials for high density packaging includingtrays, pouches, cups, bags and the like so long as the containersprovide the features described herein including gas permeability. Theproduce is packaged in a sealable and readily cold permeable container.The packages can be sealed with films, bags or lids composed of apolymer or other suitable material as known by those of ordinary skillin the art. For example, the sealing material may be a polymer material,such as polyethylene or polyvinyl chloride. In particular embodiments ofthe invention, the sealed container is oxygen-impermeable.

Embodiments of the present invention further relate to methods of makingan extended shelf-life packaged mushroom product, comprising packagingmushrooms in a sealed container together with a gas atmosphere whereinthe gas atmosphere comprises 0% to 5% by volume oxygen, 1% to 20% byvolume carbon dioxide, 0% to 20% by volume hydrogen and at least 50% byvolume nitrogen. In particular, the gas may comprise compositions byvolume as described above.

In the process of making an extended shelf-life packaged mushroomproduct, the gas may be added to a sealed container concurrently withthe addition of the mushrooms. Alternatively, the gas may be added to asealed container after the mushrooms have been added to the container.

The methods according to the present invention can provide packagedproducts that are oxygen-impermeable. The methods can further entailstoring the packaged products in a refrigerated environment. Moreover,methods of making an extended shelf-life packaged mushroom product, asdescribed herein, further provide packaged products that have ashelf-life of at least 15 days when stored at about 4° C. In someembodiments, the methods provide packaged products having a shelf-lifeof 21 days when stored in refrigerated temperatures, for example, atabout 4° C. In still other embodiments, the methods provide packagedproducts wherein the shelf-life of the packaged products can be extendedup to about 25 days when stored in refrigerated temperatures, forexample, at about 4° C.

The methods according to the present invention further produce packagedproducts that exhibit decreased growth of bacteria and other spoilagemicroorganisms compared to a packaged product packaged in a conventionalmanner. In particular, addition of a gas atmosphere as provided in themethods of the present invention contribute to decreased growth ofaerobic and anaerobic bacteria and also decreased growth of otherspoilage microorganisms, as noted above, compared to products packagedaccording to a conventional manner of packaging mushrooms. In someembodiments, methods of preparing the packaged products enable thepackaged products to exhibit improved microbial qualities compared to apackaged product packaged in a conventional manner. For example, thesemethods can result in at least a one log reduction in the amount ofaerobic bacteria contained in the packaged product when stored at about4° C. for at least 3 days compared to a packaged product packaged in aconventional manner when stored at about 4° C. for at least 3 days.

FIG. 2 provides a schematic illustrating a multi-step procedure for theassembly of a packaged product according to an embodiment of the presentinvention. More specifically, selected mushrooms are placed in a package21. The existing atmosphere is withdrawn from the sealed package 22. Agas atmosphere as described above is added to the package, which isoxygen impermeable 23. The oxygen-impermeable package 23 containing themushrooms is stored in a refrigerated temperature in a range of about 2°C. to 8° C.

Embodiments of the present invention further relate to apparatus forpackaging mushrooms comprising a plurality of processing stations for(a) removing existing air from a package comprising mushrooms and (b)adding to the package a gas mixture comprising about 0% to 5% by volumeoxygen, about 1% to 20% by volume carbon dioxide, about 0% to 20% byvolume hydrogen and at least about 50% by volume nitrogen. Inparticular, the gas may comprise compositions by volume as describedabove.

In some embodiments, the processing stations are sequentially arranged.In other embodiments, processing stations further comprise a processingstation for sealing the package to provide an air-tight seal. Theprocessing stations can be facilitated and/or modulated by a controldevice.

In particular embodiments, the apparatus enable the gas mixture to beadded to the package concurrently with the mushrooms. In still otherembodiments, the apparatus enable the gas mixture to be added to thepackage after addition of the mushrooms.

FIG. 3 provides a schematic illustrating processing stations in thestepwise assembly of packaged products according to an embodiment of thepresent invention. In particular, mushrooms are placed in a container 32and sealed with a suitable material using a sealing device 33 andtransferred to the next processing station along a conveyor belt 36. Avacuum device 34 evacuates the existing air environment from thepackage. An atmosphere injector 35 adds a gas atmosphere according toembodiments of the present invention to the package. Alternatively, themushrooms can be placed in a container and an air-tight seal can beformed concurrently with or after flushing the existing air from thepackage and adding the gas atmosphere to the package. The assemblyprocess can be facilitated and/or modulated by a control device (notshown).

Embodiments of the present invention will be further explained withreference to certain examples, which are included herein forillustration purposes only, and which are not intended to be limiting ofthe invention.

EXAMPLE 1 Methodology

Portabella, pom pom and shiitake mushrooms were provided by PhillipsMushroom Farms, Pennsylvania. All mushrooms were packaged in threedifferent atmospheric environments including air (CO), a modifiedatmosphere containing no oxygen (MA1) and a modified atmospherecontaining 3% oxygen (MA2). Samples stored under air served as controls.All samples were stored at 4° C. for 15 days.

EXAMPLE 2 Microbial Analysis

Total aerobic bacterial counts were determined on Tryptic Soy Agar (TSA)following 48 incubation at 37° C. Anaerobic bacteria were enumerated onreinforced clostridial medium (RCM) and plates were incubated at 37° C.in an anaerobic environment for 48 hours. Bacterial counts wereexpressed as log₁₀CFU/mL as shown in FIG. 1. Data were analyzed by ANOVAusing SAS. Dunnett's test was used to compare treatment means tocontrol.

EXAMPLE 3 Sensory Analysis

Sensory evaluation of samples was performed by an eight-member panel.Panelists were asked to evaluate off-odor, surface discoloration,texture (softness) and overall difference of each sample versus theappropriate control using a 7-point scale (−3=less than control, 0=sameas control and 3=more than control). Data were analyzed by ANOVA usingSAS. Dunnett's test was used to compare treatment means to control.Results are presented in the table shown in the document found atAppendix A.

EXAMPLE 4 Results

Panelists found samples packaged under modified atmosphere to be highlyacceptable compared to their respective controls. The control sampleswere judged unacceptable in that the control samples exhibited strongoff-odor, an indication of spoilage, and loss of fresh mushroom color.

Sensory acceptability correlated well with microbial analyses. Samplesstored under air had higher microbial loads (as judged by TSA and RCM)than those stored under a modified gas atmosphere.

Shelf-life extension of mushrooms by at least one week was achievedusing modified atmosphere packaging, in particular, in combination withcold storage.

The foregoing is illustrative of the present invention, and is not to beconstrued as limiting thereof. The invention is defined by the followingclaims, with equivalents of the claims to be included therein.

1. A packaged product comprising: (a) a sealed container; (b) mushrooms in said container; and (c) a gas atmosphere, said gas comprising about 0% to 5% by volume oxygen, about 1% to 20% by volume carbon dioxide, about 0% to 20% by volume hydrogen and at least about 50% by volume nitrogen.
 2. The packaged product of claim 1, wherein the mushrooms are exotic mushrooms.
 3. The packaged product of claim 2, wherein the exotic mushrooms are selected from pom pom, portabella, shiitake and combinations thereof.
 4. The packaged product of claim 1, wherein the sealed container is oxygen-impermeable.
 5. The packaged product of claim 1, wherein said gas comprises less than about 0.5% by volume oxygen.
 6. The packaged product of claim 1, wherein said gas comprises less than about 5% by volume oxygen, about 3% to 12% by volume carbon dioxide, about 0% to 10% by volume hydrogen and at least about 70% by volume nitrogen.
 7. The packaged product of claim 1, wherein said gas comprises about 3% by volume oxygen, about 10% by volume carbon dioxide and about 87% by volume nitrogen.
 8. The packaged product of claim 1, wherein said gas comprises about 10% by volume carbon dioxide, about 10% by volume hydrogen and about 80% by volume nitrogen.
 9. The packaged product of claim 1, wherein the packaged product has a shelf-life of at least 15 days when stored at 4° C.
 10. The packaged product of claim 1, wherein the packaged product exhibits decreased growth of bacteria and spoilage microorganisms compared to a packaged product packaged in a conventional manner.
 11. The packaged product of claim 1, wherein at least a one log reduction is achieved in the amount of aerobic bacteria contained in the packaged product when stored at about 4° C. for at least 3 days compared to a packaged product packaged in a conventional manner when stored at about 4° C. for at least 3 days.
 12. The packaged product of claim 1, wherein the packaged product exhibits improved sensory qualities compared to a packaged product packaged in a conventional manner.
 13. The method of making an extended shelf-life packaged mushroom product, comprising: packaging mushrooms in a sealed container together with a gas atmosphere; said gas atmosphere comprising about 0% to 5% by volume oxygen, about 1% to 20% by volume carbon dioxide, about 0% to 20% by volume hydrogen and at least about 50% by volume nitrogen.
 14. The method of claim 13, wherein the mushrooms are exotic mushrooms.
 15. The method of claim 14, wherein the exotic mushrooms are selected from pom pom, portabella, shiitake and combinations thereof.
 16. The method of claim 13, wherein the package is oxygen-impermeable.
 17. The method of claim 13, wherein the package comprises less than 0.5% by volume oxygen.
 18. The method of claim 13, wherein the packaged product has a shelf-life of at least 15 days when stored at 4° C.
 19. The method of claim 13, wherein the packaged product exhibits decreased growth of bacteria and spoilage microorganisms compared to a packaged product packaged in a conventional manner.
 20. The method of claim 13, wherein at least a one log reduction is achieved in the amount of aerobic bacteria contained in the packaged product when stored at about 4° C. for at least 3 days compared to a packaged product packaged in a conventional manner when stored at about 4° C. for at least 3 days.
 21. The method of claim 13, wherein the packaged product exhibits improved sensory qualities compared to a packaged product packaged in a conventional manner.
 22. The method of claim 13, wherein said gas comprises less than about 5% by volume oxygen, about 3% to 12% by volume carbon dioxide, about 0% to 10% by volume hydrogen and at least about 70% by volume nitrogen.
 23. The method of claim 13, wherein the shelf-life is extended up to about 25 days when compared to the shelf-life of a packaged product packaged in a conventional manner.
 24. The method of claim 13, wherein the packaged product is stored in a refrigerated environment.
 25. An apparatus for packaging mushrooms comprising a plurality of processing stations for (a) removing existing air from a package comprising mushrooms and (b) adding to the package a gas mixture comprising about 0% to 5% by volume oxygen, about 1% to 20% by volume carbon dioxide, about 0% to 20% by volume hydrogen and at least about 50% by volume nitrogen.
 26. The apparatus of claim 25, wherein the processing stations are sequentially arranged.
 27. The apparatus of claim 25, wherein said gas mixture comprises less than 5% by volume oxygen, about 5% to 10% by volume carbon dioxide, about 0% to 10% by volume hydrogen and at least about 70% by volume nitrogen.
 28. The apparatus of claim 25, wherein the plurality of processing stations further comprise a processing station for sealing the package to provide an air-tight seal. 